94 We anticipate that our general and administrative expenses will increase as a result of increased personnel costs, including stock-based compensation, expanded infrastructure and higher consulting, legal and accounting services associated with maintaining compliance with requirements of the stock exchange listing and Securities and Exchange Commission, or SEC, investor relations costs and director and officer insurance premiums associated with being a public company. Interest Expense Interest expense consists primarily of interest expense related to our convertible notes, including accretion of debt discount and debt issuance costs, which converted into shares of common stock upon the closing of our IPO. Other Income (Expense), Net Other income (expense), net primarily consists of changes in the fair value of warrants for Series B redeemable convertible preferred stock, changes in fair value of the derivative instruments and interest income. Loss on Extinguishment of Debt Loss on extinguishment of debt was recognized for the year ended December 31, 2018 related to the convertible notes issued in February 2018 which converted into shares of common stock upon closing of our IPO. Results of Operations Comparison of the Years Ended December 31, 2018 and 2017 The following table summarizes our results of operations for the periods indicated: Year Ended December 31, Change 2018 2017 Dollar Percent (in thousands) Operating expenses: Research and development ................................................... $ 18,793 $ 22,022 $ (3,229) (15)% General and administrative ................................................... 7,581 3,499 4,082 117% Loss from operations.................................................................. (26,374) (25,521) (853) 3% Interest expense (includes $3,030 and $914 attributable to related parties for the years ended December 31, 2018 and 2017, respectively) ........................................................... (5,519) (1,185) (4,334) * Other income (expense), net (includes $2,736 and $1,008 attributable to related parties for the years ended December 31, 2018 and 2017, respectively ).......................... (4,071) (1,230) (2,841) * Loss on extinguishment of debt (includes $1,587 attributable to related parties for the year ended December 31, 2018) ...... (5,479) — (5,479) * Net loss....................................................................................... $ (41,443) $ (27,936) $ (13,507) 48% * Percentage is not meaningful Research and Development Expenses Research and development expenses decreased $3.2 million, or 15%, from the year ended December 31, 2017 to the year ended December 31, 2018.